Process of making hydraulic cement.



run snares WL'L'LIAM R. WARREN,

OF NEW YORK, Y.

PROCESS OF MAKING HYDRAULIC CEMENT.

No Drawing.

To all whom it mag renown:

Be it known that 1, WILLIAM R. WARREN,

a citizen of the United States, and .a resident of the city, county, and ,State of New York, have invented certain new and useful Improvements in Processes of Making Hy- ;draulic Cement, of which the following is a specification. I f My invention relates to the production of hydraulic cement.

The purpose of! my invention is to provide an economical and eflicient process of producing a uniform grade of hydraulic cement having all the characteristics desirable in a hydraulic cement. In fact a ce ment produced by my process is in some re} spects superior to high grade Portland cements. For example it is more durable; it

is.a much. less expanding material; it is much less susceptible to harmful influences of salt solutions; and it is much less af fected by extreme temperature variations.

The various steps of my'process and the special advantages thereof will appear in the course of the following description thereof and its essential features will be pointed out in the appended claims.

In carrying out my invention I first I choose a material, or make a mixture of materials, carrying hme, (or lime and mag-.

Inesia) silica and alumina and melt the same in a suitable furnace. The furnace employed may be of any'type adapted to produce the required temperature, as for example an electric furnace, a cupola or a regenerative furnace. Whatever the form of. furnace employed,\the material is melted under non-reducing or oxidizing conditions.

Where a carbonaceous fuel, solid or gaseous, is employed these conditions may be obtained by a blast of air of sufiicient volume to produce a substantially complete -com-' bustion of' the fuel. The purpose of melting under/neutral or oxi Zing conditions is to prevent the reduction of any substantial amount of iron or other metal that may be. present in the materials in the furnace,

so that it is notneces'sary to periodically sto operations to remove the molten metal an there is'a' substantially uniform rateof melting and the melt of the: furnace is permitteld to. flow therefrom continuouslyat substantially this uniformrate. The furnace being operated under neutral or oxidi'zing, conditions, there will be substantially no molten metal carried with'the melted Specification of Letters Patent.

Application filed March 6,

Patented Jan. 5, 1915. 1914. Serial lie. was.

silicates and interfering with the operation of my process. By maintaining a substantially continuous flow-of the melt from the furnace I avoid the various evils'of interw,

mittent operation, for, Wherethere is iii ten mittent operation, the apparatusfor handling the melt during the further operation process wh-ile tending to produce less uniform results.

According to my process the non-volatile constituents of the materials with which thefurnaces are charged should contain approximately fifty per cent; of lime orlime and magnesm; Some variation from fifty *per cent. is, of course, permissible. As=at present advised, however, I believe it is not I practicable in the operation of my process,

to have more than fifty two or fifty-three per cent.v of lime, or lime andmagne's'ia. By employing-material in which the lime or lime and magnesia contents is approximately 50% of the non-volatile constituents, I find that the batch may be actually'fused or melted at. comparatively low temperatures, indeed at temperatures materially below those hitherto required for clinkering Portland cement nriixtures.- The materials to be melted may vary widely but I prefer to use stone asfound in nature, thusv avoiding expensive raw materials, and,,as

a specific instance, I may state that I have obtained excellent results by melting to: gether thirteen hundred parts of cement 'rock with one hundredparts' offs late both I broken to about twoinch pieces, in a cupola with two' hundred andfifty parts of. coke, there being introduced into the cupola a blast of air having a pressure of from sixfto seven ounces and sufficie'nt involume so that substantially all the carbon ofthe'coke is converted into carbon dioxid.

A specific melt suitable forpmy process.

and which may be produced-from such a mixture of materials, as I have mentioned,

is composed of calcium'oxid, 48%; magnesium oxid,-3%; silica, 35.5%; alumina and iron oxids, 12.5% andsodium and potassium -oxids,-l%-

mediately subdivided into small particles The melt flowing from the furnace is i'm while still molten and this subdivision is accomplished in the presence of a fine spray of an aqueous solution of one or more metallic sulfates, magnesium sulfate being in most instancespreferable.

The fine subdivision of the still molten material may be effected in various ways as, for example, by allowing the molten ma terial to flow upon a rapidly rotating drum or table in a chamber wherein a fine, spray of. solution of magnesium sulfate, saltpreferably of an alkali forming metal or metals, I

or equivalent sulfate is injected capable of increasing the hydraulic properties of the mater al.

' duces, I believe, in the resulting'cement,

'by two considerations.

both the alkali metals and the alkaline earth metals. A. five per cent. solution ofmagnesium sulfate is ordinarily satisfactory. The density of the spray must begoverned There should be enough of the solution present relatively to the amount of material flowing so that a rapid cooling and solidification of the finely divided material is effected. hand, the molten material must not be subjected to such large volume of spray that it will cool to the point of permanently retaining moisture before it can be removed from the presence of the spray; I have found. that on the average about seventy-five gallons of spray to one ton of molten material will give very satisfactory results. Under these conditions the divided particles of molten material solidify with great rapidity and fall to the bottom of the chamber contain- I ing the drum or table and the spray. By continuously removing the fallen particles of chilled material the same rapidly evaporate by their own heat the moisture remaining on them. This is important for it is impossible to make a satisfactory hydraul c cement according to this process if any moisture remains after the particles have become cold, subsequent drying being no remedy for the deterioration which such moisture e ects.

The mate ial is now a cement clinker having about fifty per cent. of lime, or lime and magnesia, contents. The material of this low line percentage when produced in the described manner need not be further heated- This low-lime material is an excellent hydraulic cement when finely ground and can beused without the addition of further lime or other material, but it is The addition of this salt pro-- salt which On the other tile constituents of the material,

slow setting and, therefore, the final step in practice, is to add about three per cent. of sulfate and hydrate of lime, which accelerates the setting time.

While it has been before suggested that molten blastfurnace slag be treated with a spray in cement making, such a method has serious disadvantages overcome by the present process. In the production of such blast furnace slag, a reducing action occurs so that sulfids and molten metal are produced. The sulfids remain in the slag resulting in the production of an inferior cement, while 'the reduction of the metals necessitates a periodic stopping of the process which is of very serious consequence, .as above eX-;

plained. Furthermore, the slag. from the blast furnace is not uniform in its composition. All these disadvantages are overcome by the present method.

The hydraulic cement produced in accordance with the foregoing process is a low-lime cement and is not, properly speaking, a Portland cement, but it will .meet all the practical tests and. requirements in service of atrue Portland cement and can be produced much more cheaply and with greater uniformity than Portland. cement can be produced, and has distinctive advantages as-hereinbefore stated.

\Vhile I have described my process in great detail and have by way of illustration .mentioned specific mixtures of materials,

characters of melt, etc., I desire it to be J understood that my process is not limited to any such detailed respects as the same may be modified in many ways without'depa'rt ing from the scope of the appended claims.

Having thus fully described my invention, what I claim and desire to protect by Letters Patent is:

1-. The process of producing cement which consists in melting under oxidizing conditions, stone containing chiefly lime, silica and alumina, the lime content in the. melt being approximately 50% of. the non-volaand treating the, material while molten with an aqueous solution of magnesium sulfate, to

produce a finely divided dry hydraulic ce ment clinker in which the lime content is approximately 50% thereof.

2. The process of producing cement which consists in melting under non-reducing conditions material containing chiefly lime (or lime and magnesia),'silica and alumina, the lime (or lime and magnesia) content of the melt being approximately 50% thereof and treating the material While molten with a solution'of a salt of an alkali forming metal capable of increasing the hydraulic properties of the material and producing a finely divided dry hydraulic cement clinker in which the lime (or lime and magnesia) content is approximately 50% thereof.

naaeee 3. The process of producing cement which consists in melting under non-reducing-com ditions, material containing chiefly lime (or lime and megne'sia), silica and alumina, the lime (or lime and magnesia) content being approximately 50% thereof, and. treating the material While molten With a solution of a Sorel cement-forming salt capable of producing Sorel cement or itsequivalent in'the finished product and thereby increasing the hydraulic properties thereof.

4. The process of producing hydraulic cement consisting in first charging a furnace with material containing lime (or lime and magnesia), silica and alumina, the lime (or lime and magnesia) content-thereof being approximately 50% of the non-volatile constituents of said materials, melting the same in said furnace under non-reducing conditions, subdividing thesilicates from said furnace, While still molten, into small par ticles in the presence of a spray of a solution of an alkali forming metal capable of increasing the hydraulic properties of the finished product, promptly removing the solid clinker from the presence of the spray,

and grinding the, dry clinker with a small percentage of a material adapted to accelerate the set of the cement.

5. The process of producing hydraulic cement consisting in first charging'a furnace with material containing lime (or lime and magnesia), silica and alumina, the lime (or finished product and producing a lime and megnesia) content thereof being approximately 50% of the Von-volatile constituents of said materials, melting thesame in said furnace, subdividing the sihcates 'fromsaid furnace While still molten into small particles in the presence of a spray -of a solution of one or more salts capable of increasing the hydraulic properties of I the finished product, removing the solid clinker from the presence of the spray aiid containing lime (or lime and 'magnesialf silica and alumina, the\ lime (or lime and magnesia) content thereof being apprexie mately 50% of the non-volatile. constituents -of said material, melting the same under non-reducing conditions, and treatingrthe molten mass With a solution of one or more salts of alkali forming metals capable of increasing the hydraulic properties of the Vided dry hydraulic cement clinker in which the lime (or lime and magnesia) content is approximately 50% thereof.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing Witnesses;

- WILLIAM R. WARREN. l/Vitnesses: f W. Wm'r a, EDWIN Snsnn'f 

